/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.catalina;

import javax.servlet.Servlet;
import javax.servlet.ServletException;
import javax.servlet.UnavailableException;

/**
 * A <b>Wrapper</b> is a Container that represents an individual servlet
 * definition from the deployment descriptor of the web application. It provides
 * a convenient mechanism to use Interceptors that see every single request to
 * the servlet represented by this definition.
 * <p>
 * Implementations of Wrapper are responsible for managing the servlet life
 * cycle for their underlying servlet class, including calling init() and
 * destroy() at appropriate times, as well as respecting the existence of the
 * SingleThreadModel declaration on the servlet class itself.
 * <p>
 * The parent Container attached to a Wrapper will generally be an
 * implementation of Context, representing the servlet context (and therefore
 * the web application) within which this servlet executes.
 * <p>
 * Child Containers are not allowed on Wrapper implementations, so the
 * <code>addChild()</code> method should throw an
 * <code>IllegalArgumentException</code>.
 * 
 * @author Craig R. McClanahan
 * @version $Id: Wrapper.java 939350 2010-04-29 15:36:29Z kkolinko $
 */

public interface Wrapper extends Container {

	// ------------------------------------------------------------- Properties

	/**
	 * Return the available date/time for this servlet, in milliseconds since
	 * the epoch. If this date/time is in the future, any request for this
	 * servlet will return an SC_SERVICE_UNAVAILABLE error. If it is zero, the
	 * servlet is currently available. A value equal to Long.MAX_VALUE is
	 * considered to mean that unavailability is permanent.
	 */
	public long getAvailable();

	/**
	 * Set the available date/time for this servlet, in milliseconds since the
	 * epoch. If this date/time is in the future, any request for this servlet
	 * will return an SC_SERVICE_UNAVAILABLE error. A value equal to
	 * Long.MAX_VALUE is considered to mean that unavailability is permanent.
	 * 
	 * @param available
	 *            The new available date/time
	 */
	public void setAvailable(long available);

	/**
	 * Return the context-relative URI of the JSP file for this servlet.
	 */
	public String getJspFile();

	/**
	 * Set the context-relative URI of the JSP file for this servlet.
	 * 
	 * @param jspFile
	 *            JSP file URI
	 */
	public void setJspFile(String jspFile);

	/**
	 * Return the load-on-startup order value (negative value means load on
	 * first call).
	 */
	public int getLoadOnStartup();

	/**
	 * Set the load-on-startup order value (negative value means load on first
	 * call).
	 * 
	 * @param value
	 *            New load-on-startup value
	 */
	public void setLoadOnStartup(int value);

	/**
	 * Return the run-as identity for this servlet.
	 */
	public String getRunAs();

	/**
	 * Set the run-as identity for this servlet.
	 * 
	 * @param runAs
	 *            New run-as identity value
	 */
	public void setRunAs(String runAs);

	/**
	 * Return the fully qualified servlet class name for this servlet.
	 */
	public String getServletClass();

	/**
	 * Set the fully qualified servlet class name for this servlet.
	 * 
	 * @param servletClass
	 *            Servlet class name
	 */
	public void setServletClass(String servletClass);

	/**
	 * Gets the names of the methods supported by the underlying servlet.
	 * 
	 * This is the same set of methods included in the Allow response header in
	 * response to an OPTIONS request method processed by the underlying
	 * servlet.
	 * 
	 * @return Array of names of the methods supported by the underlying servlet
	 */
	public String[] getServletMethods() throws ServletException;

	/**
	 * Is this servlet currently unavailable?
	 */
	public boolean isUnavailable();

	// --------------------------------------------------------- Public Methods

	/**
	 * Add a new servlet initialization parameter for this servlet.
	 * 
	 * @param name
	 *            Name of this initialization parameter to add
	 * @param value
	 *            Value of this initialization parameter to add
	 */
	public void addInitParameter(String name, String value);

	/**
	 * Add a new listener interested in InstanceEvents.
	 * 
	 * @param listener
	 *            The new listener
	 */
	public void addInstanceListener(InstanceListener listener);

	/**
	 * Add a mapping associated with the Wrapper.
	 * 
	 * @param mapping
	 *            The new wrapper mapping
	 */
	public void addMapping(String mapping);

	/**
	 * Add a new security role reference record to the set of records for this
	 * servlet.
	 * 
	 * @param name
	 *            Role name used within this servlet
	 * @param link
	 *            Role name used within the web application
	 */
	public void addSecurityReference(String name, String link);

	/**
	 * Allocate an initialized instance of this Servlet that is ready to have
	 * its <code>service()</code> method called. If the servlet class does not
	 * implement <code>SingleThreadModel</code>, the (only) initialized instance
	 * may be returned immediately. If the servlet class implements
	 * <code>SingleThreadModel</code>, the Wrapper implementation must ensure
	 * that this instance is not allocated again until it is deallocated by a
	 * call to <code>deallocate()</code>.
	 * 
	 * @exception ServletException
	 *                if the servlet init() method threw an exception
	 * @exception ServletException
	 *                if a loading error occurs
	 */
	public Servlet allocate() throws ServletException;

	/**
	 * Return this previously allocated servlet to the pool of available
	 * instances. If this servlet class does not implement SingleThreadModel, no
	 * action is actually required.
	 * 
	 * @param servlet
	 *            The servlet to be returned
	 * 
	 * @exception ServletException
	 *                if a deallocation error occurs
	 */
	public void deallocate(Servlet servlet) throws ServletException;

	/**
	 * Return the associated servlet instance.
	 */
	public Servlet getServlet();

	/**
	 * Return the value for the specified initialization parameter name, if any;
	 * otherwise return <code>null</code>.
	 * 
	 * @param name
	 *            Name of the requested initialization parameter
	 */
	public String findInitParameter(String name);

	/**
	 * Return the names of all defined initialization parameters for this
	 * servlet.
	 */
	public String[] findInitParameters();

	/**
	 * Return the mappings associated with this wrapper.
	 */
	public String[] findMappings();

	/**
	 * Return the security role link for the specified security role reference
	 * name, if any; otherwise return <code>null</code>.
	 * 
	 * @param name
	 *            Security role reference used within this servlet
	 */
	public String findSecurityReference(String name);

	/**
	 * Return the set of security role reference names associated with this
	 * servlet, if any; otherwise return a zero-length array.
	 */
	public String[] findSecurityReferences();

	/**
	 * Increment the error count value used when monitoring.
	 */
	public void incrementErrorCount();

	/**
	 * Load and initialize an instance of this servlet, if there is not already
	 * at least one initialized instance. This can be used, for example, to load
	 * servlets that are marked in the deployment descriptor to be loaded at
	 * server startup time.
	 * 
	 * @exception ServletException
	 *                if the servlet init() method threw an exception
	 * @exception ServletException
	 *                if some other loading problem occurs
	 */
	public void load() throws ServletException;

	/**
	 * Remove the specified initialization parameter from this servlet.
	 * 
	 * @param name
	 *            Name of the initialization parameter to remove
	 */
	public void removeInitParameter(String name);

	/**
	 * Remove a listener no longer interested in InstanceEvents.
	 * 
	 * @param listener
	 *            The listener to remove
	 */
	public void removeInstanceListener(InstanceListener listener);

	/**
	 * Remove a mapping associated with the wrapper.
	 * 
	 * @param mapping
	 *            The pattern to remove
	 */
	public void removeMapping(String mapping);

	/**
	 * Remove any security role reference for the specified role name.
	 * 
	 * @param name
	 *            Security role used within this servlet to be removed
	 */
	public void removeSecurityReference(String name);

	/**
	 * Process an UnavailableException, marking this servlet as unavailable for
	 * the specified amount of time.
	 * 
	 * @param unavailable
	 *            The exception that occurred, or <code>null</code> to mark this
	 *            servlet as permanently unavailable
	 */
	public void unavailable(UnavailableException unavailable);

	/**
	 * Unload all initialized instances of this servlet, after calling the
	 * <code>destroy()</code> method for each instance. This can be used, for
	 * example, prior to shutting down the entire servlet engine, or prior to
	 * reloading all of the classes from the Loader associated with our Loader's
	 * repository.
	 * 
	 * @exception ServletException
	 *                if an unload error occurs
	 */
	public void unload() throws ServletException;

}
